Let's write the parametric line
(x,y,z) = (0,2,8) + t(5,-1,4)
(5,-1,4) is called the direction vector of the line. It's normal to the plane
5x - y + 4z = constant
We get the constant by substituting the point (3,0,7),
5x - y +4z = 5(3) - 0 + 4(7) = 43
5x - y +4z = 43
First subtract 4 from btoh sides of the equation
4 - 4 - 2x < 6-4
-2x < 2
Now divide both sides by -2
x > -1
NOTE: when dividing by a negative as above the inequality sign is flipped.
Answer:
m/s*3
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By adding x = -7 so (4*-7-8y=0) y=(-7/(8*4))=3.5
528= 8x+240
288=8x
x=36 hours